Bis(3,5-dihydrocarbyl-4-hydroxyphenyl)hydrogen phosphonates



limited States Patent Q 3,493,638 BIS(3,5-DIHYDROCARBYL-4-HYDROXYPHENYL) HYDROGEN PHOSPHONATES Bernard R. Meltsner, RoyalOak, Mich., assignor to Ethyl Corporation, New York, N.Y., a corporationof Virginia No Drawing. Continuation-impart of application Ser. No.505,990, Nov. 1, 1965. This application Nov. 21, 1966, Ser. No. 595,613

Int. Cl. C07f 9/12; C08f 51/58; C10m 1/46 US. Cl. 260953 4 ClaimsABSTRACT OF THE DISCLOSURE A new class of antioxidants is prepared bythe reaction of phosphorous trihalides with2,6-dihydrocarbyl-p-hydroquinones. A typical example is the productprepared by the reaction of phosphorous trichloride with2,6-ditert-butyl-p-hydroquinone. A major component of the reactionproduct has been identified astris(3,5-di-tertbutyl-4-hydroxyphenyl)phosphite. Another componentpresent in lesser amounts isbis(3,5-di-tert-butyl-4-hydroxyphenyDhydrogen phosphonate. Both thereaction product and the puretris(3,5-di-tert-butyl-4-hydroxyphenyl)phosphite have been found to beantioxidants in organic materials, especially in polypropylene andlubricating oil. They also exhibit a synergistic antioxidant respondwith dialkyl thiodialkanoates such as dilaurylthiodipropionate.

This application is a continuation-in-part of co-pending applicationSer. No. 505,990, filed Nov. 1, 1965 now abandoned.

Most organic materials undergo degradation in the presence of oxygen.This degradation is accelerated at increased temperatures. Frequently,high temperatures are encountered during the processing of thesematerials in manufacturing operations and thus some form of stabilizeris required for many materials, even during the manufacturing stage.Other materials are not subject to extremes in temperature duringmanufacture, but even these undergo degradation on aging.

An object of this invention is to provide an additive capable ofpreventing degradation of organic materials due to oxygen. A furtherobject of this invention is to provide organic materials that are stableagainst the effects of oxygen at elevated temperatures duringmanufacture and also stable during long periods of aging under useconditions. A particular object is to provide a polyolefin (e.g.,polypropylene) of exceptional hightemperature stability and capable ofresisting degradation due to oxygen during long periods of use. Otherobjects will become apparent from the following description of theinvention.

The above and other objects are accomplished by providing a productproduced by the process comprising reacting a phosphorous trihalideselected from the group consisting of phosphorous trichloride andphosphorous tribromide with a hydroquinone, said hydroquinone having theformula:

wherein R is selected from the group consisting of alphabranched alkylradicals containing from 3-18 carbon atoms, alpha-branched aralkylradicals containing from 218 carbon atoms and cycloalkyl radicalscontaning from 618 carbon atoms; and R is selected from the groupconsisting of alkyl radicals containing from 1-18 carbon atoms, aralkylradicals containing from 7-18 carbon atoms, aryl radicals containingfrom 6-18 caratoms and cycloalkyl radicals containing from 6-18 carbonatoms, in the mole ratio of from about 2-4 moles of said hydroquinoneper mole of said phosphorous trihalide at a temperature of from 0 to 200C.

The products of this invention are readily prepared by reacting a2,6-dihydrocarbyl-p-hydroquinone having Formula I with a phosphoroustrihalide. Although any of the phosphorous trihalides may be employed,the preferred reactants are phosphorous tribromide and phosphoroustrichloride and especially phosphorous trichloride because of its lowcost, availability and excellent results obtained with its use.

Some examples of useful p-hydroquinones having Formula I are:

2-methyl-6-tert-butyl-p-hydroquinone 2-ethy1-6-isopropyl-p-hydroquinoneZ-methyl-6-cyclohexyl-p-hydroquinone 2-n-propyl-6- u-methylbenzyl-p-hydroquinone 2-methyl- 6- u-methylbenzyl -p-hydroquinone 3-methyl-6-a,u-dimethylbenzyl-p-hydroquinone 2-phenyl-6-tert-butyl-6-hydroquinoneIn a preferred embodiment, both R and R in Formula I are alpha-branchedhydrocarbyl radicals. Some representative examples of thesehydroquinones are:

2,6-diisopropyl-p-hydroquinone 2,6-dicyclohexyl-p-hydroquinone2,6-di-sec-butyl-p-hydroquinone 2-isopropyl-6-tert-butyl-p-hydroquinone2-tert-butyl-6- a-methylbenzyl -p-hydroquinoneZ-tert-butyl-6-cyclohexyl-p-hydroquinoneZ-tert-dodecyl-6-sec-octadecyl-p-hydroquinone2-tert-nonyl-6-sec-octyl-p-hydroquinone In a further preferredembodiment, both R and R in Formula I are tertiary alkyl radicals. Thesemay be illustrated by the following hydroquinones.

2,6-di-tert-amyl-p-hydroquinone 2,6-di-tert-octyl-p-hydroquinone2,6-di-tert-dodecyl-p-hydroquinone 2,6-di-tert-octadecyl-p-hydroquinone2,6-di a,a-dimethylbenzyl -p-hydroquinone2-tert-butyl-6-tert-octyl-p-hydroquinone2-tert-butyl-6-(a,a-dimethylbenzyl)-phydroquinoneZ-tert-amyl-6-tert-octadecyl-p-hydroquinone The most preferredhydroquinone of Formula I is 2,6-di-tert-butyl-p-hydroquinone.

The 2,6-dihydrocarbyl-p-hydroquinones can be prepared by any of themethods available in the art such as the oxidation of the corresponding2,6-dihydrocarbylp-aminophenol to the 2,6-di-hydrocarbyl-benzoquinonefollowed by reduction to the 2,6-di-hydrocarbyl-p-hydroquinone. Anespecially useful method for preparing the preferred hydroquinones isthrough the air oxidation of the proper2,6-di-tert-alkyl-4-tert-butylphenol. The air oxidation of suchcompounds leads to 2,6-di-tert-alkyl-pbenzoquinones which are readilyconverted to the corresponding hydroquinone by reduction. The method isdescribed in detail by H. G. Braxton et al. in US. 3,213,114.

The stoichiometry of the reaction requires three moles of the2,6-dihydrocarbyl-p-hydroquinone per mole of phosphorous trihalide. Moreor less of the hydroquinone can be employed. A useful range is from 2-4moles of the hydroquinone per mole of phosphorous trihalide. A morepreferred range is from about 2.8 to 3.1 moles per mole of phosphoroustrihalide. A most preferred range is from about 2.9 to 3 moles of2,6-dihydrocarbyl-p-hydroquinone per mole of phosphorous trihalide.

The reaction between the hydroquinones and the phosphorous trichloridecan be conducted by adding the phosphorous trichloride to thehydroquinone or by adding the hydroquinone to the phosphoroustrichloride. The preferred method is to add the phosphorous trichlorideto the hydroquinone.

The reaction may be conducted in the presence or absence of a solvent.Usually it is preferred to employ a solvent because this makes it easierto moderate the reaction and also to purify the product. Preferredsolvents are those in which the reactants are soluble and which areinert to the reactants or products under the reaction conditions. Someexamples of these are ethers such as diethyl ether, ethyl butyl ether,di-n-propyl ether, ethylene glycol diethyl ether, diethyleneglycoldimethyl ether, and the like; esters such as ethyl acetate, amylacetate, ethyl butyrate, and the like; and hydrocarbons such as hexane,heptane, isooctane, kerosene, petroleum ether (mixtures of low boilinghydrocarbons), mineral spirits, and the like. The more preferredsolvents are hydrocarbons having a boiling point of from about 50 toabout 200 C. Some examples of highly preferred solvents are toluene andxylene.

The reaction should be conducted at a temperature high enough so thatthe reaction proceeds at a reasonable rate, but not so high as to causedegradation of the product. A preferred temperature range is from aboutC. up to about 200 C. A more preferred range is from 20 to 150 C., and amost preferred temperature range is from about 50 to 100 C.

The reaction involves the evolution of a hydrogen halide, for example,HCl, and thus can be conducted in the presence of a hydrogen halideacceptor. Especially suitable hydrogen halide acceptors are the tertiaryamines such as pyridine or triethylamine. When a hydrogen halideacceptor is employed the preferred quantity used in an amount sufficientto react with the hydrogen halide evolved during the process.

The reaction may be conducted in the presence of air, although it isusually preferred to carry the reaction out under a relatively inertatmosphere. An inert atmosphere removes the danger of explosions andlessens the likelihood of contaminating the product through oxidation.Although the process can be conducted at temperature both below andabove atmospheric pressure, it is normally conducted at atmosphericpressure.

The addition of the phosphorous trihalide to the2,6-dihydrocarbyl-p-hydroquinone usually takes from about minutes toseveral hours, depending upon the size of the reaction and theefficiency of heat removal. The addition time is not critical and can becarried out at as high a rate as permitted by the cooling meansavailable. Under normal conditions the addition is readily completed infrom about 30 minutes to an hour. Preferably, the reaction is stirred atthe reaction temperature for a short period following the completion ofthe addition of the reactants. Under most circumstances the reaction iscomplete in from about 0.5 to 8 hours following completion of addition.A preferred reaction time is from about one to 4 hours, and a. mostpreferred reaction time is from about 2 to 3 hours.

The product may be recovered by any of the means known to those skilledin the art. One useful method when a tertiary amine hydrogen halideacceptor is employed is to first filter off the tertiary amine hydrogenhalide complex, following which all solvent is distilled from thefiltrate, leaving a semi-liquid residue. This residue may be usd as isor may be converted to a crystalline form by dissolving in a hotaliphatic hydrocarbon such as hexane and, upon cooling, the product willcrystallize in good yields.

In another method of recovering the product the reaction mass is merelywashed with water at the end of the reaction period to remove anyresidual hydrogen halide. It is then preferably washed with a slightlybasic solution (e.g., dilute Na CO solution) to neutralize any remainingacid. The solvent is then removed as previously.

The product can be recovered by merely evaporating any solvent employedand using the residue as is. In still another embodiment the solution ofthe stabilizer may be used directly in blending with the organicmaterials requiring stabilization. Thus, when the reaction is conductedin a toluene solvent, the toluene solution of the stabilizer may bewashed and neutralized to remove acidic material and then sprayeddirectly onto, for example, bulk polypropylene. The solvent is thenevaporated off and the bulk polypropylene is ready for processing (e.g.,molding, extrusion, and the like). Another method is to add the solutionof the stabilizer to a solution of the material to be stabilized andthen to remove the solvent. This method is most useful when adding thestabilizer to polymers prepared in solvents such as polycis-butadiene.

The reaction of phosphorous trihalides with hydroquinones of Formula Ihas been found to give a mixture of products. Several of these resultingfrom the reaction of phosphorous trichloride and2,6-di-tert-butyl-hydroquinone have been separated and identified. Theseare the major product, tris(3,5-di-tert-buty1-4-hydroxyphenyl)-phosphite, and lesser amounts of bis(3,5-di-tert-butyl-4-hydroxyphenyl)hydrogen phosphonate. These new compounds can berepresented by the formula:

wherein x is an integer from 0-1, R is selected from the groupconsisting of alpha-branched alkyl radicals containing from 3-18 carbonatoms, alpha-branched aralkyl radicals containing from 8-18 carbon atomsand cycloalkyl radicals containing from 6-18 carbon atoms; and R isselected from the group consisting of alkyl radicals containing from1-18 carbon atoms, aralkyl radicals containing from 7-18 carbon atoms,aryl radicals containing from 6-18 carbon atoms and cycloalkyl radicalscontaining from 6-18 carbon atoms.

These new compounds may be used as antioxidants in the form of thereaction product which they comprise or they may be separated and usedindividually or as mixtures. They are effective antioxidants eitherindividually, in mixtures, or in the reaction product. Of course, thereaction product is an excellent antioxidant in its own right and,although two of the types of components found in it have beenidentified, it is not possible to adequately define the reaction productby its components and hence separate embodiments of the invention arerepresented by the individual compounds of Formula II and the productproduced by the reaction of phosphorous trihalides with thehydroquinones of Formula I. A feature of the reaction products describedherein is that, although they contain lesser amounts of the veryeffective tris(3,5-dihydrocarbyl-4-hydroxyphenyl)phosphites than doesthe purified material, they exhibit a similar degree of antioxidanteffectiveness, and thus represent an economic advantage.

The following compounds serve to illustrate new tris(3,5,-dihydrocarbyl-4 hydroxyphenyl)phosphites represented by Formula IIwhen x is zero.

tris (3 -methyl-5-tert-butyl-4-hydroxyphenyl phosphite tris (3-ethyl-5-isopropyl-4-hydroxyphenyl phosphite tris3-methyl-5-cyclohexyl-4-hydroxyphenyl phosphite tris 3-n-propyl-5-a-methylbenzyl -4-hydroxyphenyl) phosphite tris(3-methyl-5-(x-methylbenzyl)-4-hydroxypehnyl) phosphitetris(3-methyl-5-(a,a-dimethylbenzyD-4-hydroxyphenyl) phosphitetris(3-phenyl-5-tert-butyl-4-hydroxyphenyl) phosphite In a preferredembodiment both R and R are alphabranched hydrocarbyl radicals. Somerepresentative examples of these compounds are:tris(3,S-diisopropyl-4-hydroxyphenyl)phosphite tris (3 ,5dicyclohexyl-4-hydroxyphenyl phosphite tris 3,5-di-sec-butyl-4-hydroxyphenyl phosphite tris3-isopropyl-5-tert-butyl-4-hydroxyphenyl phosphite tris 3-tert-butyl-5-a-methylbenzyl -4-hydroxybenzyl) phosphite tris 3-tert-butyl-5-cyclohexyl-4-hydrc.xyphenyl) phosphite tris3-tert-dodecy1-5 -sec-octadecyl-4-hydroxypheny1) phosphite tris3-tert-nonyl-S-sec-octyl-4-hydroxyphenyl phosphite In a more preferredembodiment both R and R are tertiary alkyl radicals. These may beillustrated by the following compounds.tris(3,5-di-tert-amyl-4-hydroxyphenyl)phosphite tris 3 ,5-di-tert-octyl-4-hydroxyphenyl phosphite tris (3 ,5-di-tert-dodecyl-4-hydroxyphenyl phosphitetris(3,5-di-tert-octadecyl-4-hydroxyphenyl)phosphitetris(3,5-di-(a,a-dimethylbenzyl)-4-hydroxyphenyl) phosphite tris3-tert-butyl-S-tert-octyl-4-hydroxyphenyl phosphitetris(3-tert-butyl-5-(a, x-dimethylbenzyl)-4-hydroxy phenyl phosphitetris(3-tert-amyl-5-tert-octadecyl-4-hydroxyphenyl) phosphite In a mostpreferred embodiment the tris(3,5-dihydrocarbyl-4-hydroxyphenyl)phosphite is tris(3,5-di-tert-butyl-4-hydroxyphenyl phosphite.

The following examples serve to illustrate the new bis (3,5-dihydroxycarbyl 4 hydroxyphenyl)hydrogen phosphonates represented byFormula II when x is 1.bis(3-methyl-5-tert-butyl-4-hydroxyphenyl)hydrogen phosponate bis3-ethyl-5 -isopropy1-4-hydroxyphenyl hydrogen phosphonate bis3-methyl-5-cyclohexyl-4-hydroxyphenyl hydrogen phosphonate bis3-n-propyl-5- a-methylbenzyl) -4-hydroxyphenyl) hydrogen phosponate bis3methyl-5 u-methylbenzyl -4-hydroxyphenyl) hydrogen phosphonatebis(3-methyl-5-(a,a-dimethylbenzyl)-4-hydroxyphenyl) hydrogen phosponatebis 3 -phenyl-5-tert-butyl-4-hydroxyphenyl hydrogen phosphonate In apreferred embodiment both R and R are alphabranched hydrocarbylradicals. Some representative examples of these compounds are:bis(3,5-diisopropyl-4-hydroxyphenyl)hydrogen phosphonate bis (3,5-dicyclohexyl-4-hydroxyphenyl hydrogen phosphonatebis(3,5-di-sec-butyl-4-hydroxyphenyl)hydrogen phosphonatebis(3-isopropyl-5-tert-butyl-4-hydroxyphenyl)hydrogen phosphonate bis3-tert-butyl5- u-methylbenzyl -4-hydroxyphenyl) hydrogen phosphonate bis(3 -tert-butyl-5-cyclohexy1-4-hydroxyphenyl hydrogen phosphonate bis3-tert-dodecyl-S-sec-octadecyl-4-hydroxyphenyl) hydrogen phosphonatebis(3-tert-nonyl-S-sec-octyl-4-hydroxyphenyl)hydrogen phosphonate 6 In amore preferred embodiment both R and R are tertiary alkyl radicals.These may be illustrated by the following compounds.

bis 3 ,5 -di-tert-amyl-4-hydroxyphenyl) hydrogen phosphonate bis 3 ,5-di-tert-octyl-4-hydroxy phenyl hydrogen phosphonate bis 3 ,5-di-tert-dodecyl-4-hydroxyphenyl hydro gen phosphonate bis 3,5-di-tert-octadecyl-4-hydroxyphenyl hydrogen phosphonate bis 3 ,5 -diax-dimethylbenzyl -4-hydroxyphenyl hydrogen phosphonate bis3-tert-butyl-S-tert-octyl-4-hydroxyphenyl) hydrogen phosphonate bis3-tert-buty1-5 a,a-dimethylbenzyl) -4 hydroxyphenyl) hydrogenphosphonate bis 3-tert-amyl-S-tert-octadecyl-4-hydroxyphenyl) hydrogenphosphonate In a most preferred embodiment thebis(3,5-dihydrocarbyl-4-hydroxyphenyl)hydrogen phosphonate isbis(3,5-ditert-butyl-4-hydroxyphenyl) hydrogen phosphonate.

In the above recitation and in Formula II the compounds when x is 1 arenamed as hydrogen phosphonates. This represents the tautomeric form ofthe mono-acid phosphite. The accepted theory is that both forms exist inan equilibrium as shown by the following equation.

1'12 Hence, in the present invention these two materials are equivalent.

In the foregoing description, many of the preferred R and R radicals arereferred to as alpha-branched radicals. These are radicals wherein thecarbon atom through which the radical bonds to the benzene ring is alsobonded with at least two carbon atoms other than the carbon atom in thebenzene ring. In other words, alpha-branched radicals are those commonlyreferred to as secondary or tertiary radicals such as the isopropyl andtert-butyl radicals.

The following examples will serve to illustrate the preparation of theadditives of the present invention. All parts are parts by weight unlessotherwise specified.

EXAMPLE 1 To a reaction vessel equipped with a stirrer, thermometer,reflux condenser and liquid addition means was charged 25 parts of2.6-di-tert-butyl-p-hydroquinone, 88 parts of benzene and 11.4 parts oftriethylamine. Nitrogen was swept through the reaction vessel to removeall oxygen and a nitrogen atmosphere was maintained over the reactantsfor the remainder of the reaction period. A separate solution of 5.15parts of phosphorous trichloride and 22 parts of benzene was added tothe reaction vessel, while stirring, over a period of 40 minutes. Thereaction, which occurred spontaneously, was exothermic and the reactiontemperature was maintained at 20 to 30 C. during the addition period byexternal cooling. Hydrogen chloride formed during the reaction reactedimmediately With the triethylamine and formed a precipitate. Thereaction mixture was allowed to stir at room temperature for eight hoursand then the reaction mass was filtered to remove the triethylaminehydrochloride precipitate. The filtrate was washed with water and thendried over anhydrous sodium sulfate. The sodium sulfate was then removedby filtration, following which the benzene solvent was removed from thefiltrate by slowly heating the filtrate to 50 to 60 C., while slowlyreducing the pressure to about 10 mm. The viscous semi-solid residue wasdissolved in 100 parts of hot hexane. The hexane solution was thencooled causing the product to precipitate as white crystals having amelting point of 148-150 C. The infrared spectra for this material wasconsistent with the structure for tris(3,5 di tert butyl 4hydroxyphenyl)phosphite. The product was subjected to carbon, hydrogenand phosphorus elemental analysis. The results of this analysis were:carbon-72.3 percent; hydrogen9.19 percent, and phosphorus-4.7 percent.The calculated carbon, hydrogen and phosphorus content for3,5-di-tert-butyl-4-hydroxyphenyl phosphite is: carbon72.6 percent;hydrogen9.14 percent, and phosphorus4.5 percent. Thus, therecrystallized material prepared in Example 1 was identified astris(3,5-di-tert-butyl-4-hydroxyphenyl)phosphite.

EXAMPLE 2 To a reaction vessel equipped as in Example 1 is added 667parts of 2,6-di-tert-butyl-phydroquinone and 1500 parts of toluene.Nitrogen is passed through the vessel until all air has been removed anda nitrogen atmosphere is maintained throughout the remainder of thereaction. While stirring, the vessel contents are heated to the refluxtemperature of the solvent. While maintaining the reaction at reflux,137.5 parts of phosphorous trichloride are fed over a one hour period.Cooling is effected by reflux of the solvent. Following the phosphoroustrichloride addition, the reaction is refluxed for one additional hour.It is then allowed to cool and immediately upon dropping below 90 C.,1000 parts of water are added to the reaction vessel and the mixturestirred for 15 minutes. The water is drained off and the reactants arethen washed with 1000 parts of a 5 percent sodium carbonate solution.This solution is drained off and the toluene solvent is then removed byreducing the pressure in the reaction vessel to 50 mm. and slowlydistilling out the toluene until the reaction vessel contents reach 150C. The remaining material is dissolved in a minimum amount of hot hexaneand the hexane solution is then cooled to C., causing the product toprecipitate, forming a slurry. The reaction mass is then filtered andthe product, tris- (3,S-di-tert-butyl-4-hydroxyphenyl)phosphite, isobtained.

EXAMPLE 3 To a reaction vessel equipped as in Example 1 is added 954parts of 2,6-di(a-methylbenzyl)-p-hydroquinone and 3000 parts of xylene.While stirring, 140 parts of phosphorous trichloride are added over aperiod of 4 hours while maintaining the reaction temperature at 30 C.through external cooling. Following the phosphorous trichlorideaddition, the reaction contents are stirred for 7 additional hours at 30C., and then the temperature is slowly raised to 100 C. during anadditional one hour period. The reaction mass is then cooled and washedtwice with 1000 parts of water each. The reaction mass is then treatedwith 1000 parts of a percent sodium carbonate solution. Following this,the xylene solvent is removed by distilling out the solvent at 30 mm. ofpressure until the reaction vessel attains a temperature of 150 C. Theresidue is recrystallized twice from a minimum quantity of petroleumether (B.P. 60-70 C.), yielding tris- (3 ,5 -dia-methylb enzyl-4-hydroxyphenyl phosphite.

In the above example equal mole quantities of other2,6-dihydrocarbyl-p-hydroquinones can be employed to give thecorresponding tris(3,5'dihydrocarbyl-4-hydroxyphenyl)phosphite. Forexample, the use of 2,6-diisopropyl-p-hydroquinone yieldstris(3,5-diisopropyl-4-hydroxyphenyl)phosphite. The use of2,6-di-sec-butyl-p-hydroquinone yields tris(3,S-di-sec-butyl-4-hydroxyphenyl)phosphite. The use of2,6-di-tert-octyl-p-hydroquinone yieldstris(3,S-di-tert-octyl-4-hydroxyphenyl)phosphite. The use of2,6-dicyclohexyl-p-hydroquinone yieldstris(3,5-dicyclohexyl-4-hydroxyphenyl)phosphite. The use of2,6-ditert-octadccyl-p-hydroquinone yieldstris(3,5-di-tert-octadecyl-4-hydroxyphenyl)phosphite. The use of2-methyl-6- (a,a-dimethylbenzyl -p-hydroquinone yields tris 3-methyl-5-(a,oc dimethylbenzyl)-4-hydroxyphenyl]phosphite. The use of2-(2,4-di-tert-butylphenyl)-6-tert-dodecyl-p-hydroquinone yields tris 3-2,4-di-tert-butylphenyl) -5-tert-dodecyl-4-hydroxyphenyl]phosphite.

In like manner, equal mole quantities of other phosphorus halides can beused, such as phosphorous tribromide, with good results.

EXAMPLE 4 In a reaction vessel equipped as in Example 1 was placed 39.25parts of 2,6-di-tert-butyl-p-hydroquinone, 155 parts of toluene, and18.9 parts of triethylamine. The mixture was stirred and cooled to 12 C.Over a period of about 1.5 hours, 8.62 parts of phosphorous trichloridewas added while keeping the temperature below about 22 C. The mixturewas then stirred for 21.5 hours at about 20-25 C. Following this, themixture was washed three times with water and then with a dilute (0.23weight percent) sodium bicarbonate solution. It was finally washed againwith water. The reaction vessel was then sealed and the pressure reducedto 81 mm. Hg. The toluene and residual water were distilled out undervacuum until the liquid temperature reached 104 C. at 35 mm. Hg. Theresidue was cooled to 69 C. and 91.5 parts of isooctane was added. Themixture was stirred and heated to reflux. The solution was then cooledto 5 C. and the reaction product which precipitated was removed byfiltration. Its melting point was 118128 C. A small sample was subjectedto thin layer chromatographic separation using a silica gel impregnatedpaper and a henzene eluting solvent. The chromatographic strip wasdeveloped using iodine vapor and showed two substantial components.Infrared analysis showed the main component to betris(3,5-di-tert-butyl-4-hydroxyphenyl)phosphite.

A second component was separated from the reaction mixture as follows. Asample of the reaction product was dissolved in hot isopropanol and thesolution was cooled, causing some material to precipitate. Theprecipitate was filtered off and then water was added to the isopropanolfiltrate until it began to haze. It was allowed to stand at roomtemperature and some further solids precipitated. These solids weresubjected to thin layer chromatographic separation and showed to be asingle compound. They were then recrystallized, first from abenzene-isooctane mixture and then from benzene. The melting point wasthen 146- 150 C. Analysis showed the composition to contain: carbon-68.6percent; hydrogen--8.8 percent; phosphorus 6.3 percent. Theoreticalanalysis for bis(3,5-di-tert-butyl- 4-hydroxyphenyl)hydrogen phosphonateis: carb0n-68.3 percent; hydrogen8.89 percent; phosphorus-6.7 percent. Anuclear magnetic resonance spectrum was obtained for the compound andshowed it to be a hydrogen phosphonate. Thus, a second compound wasisolated from the reaction product and identified asbis(3,5-di-tert-butyl- 4-hydroxyphenyl)hydrogen phosphonate. Thiscompound is also an effective antioxidant, especially in polypropylene.Furthermore, the crude reaction product which contained the twoidentified ingredients in addition to other unknown material was foundto be more effective on a weight basis in stabilizing polypropylene thanpurified tris (3,S-di-tert-butyl-4-hydroxyphenyl)phosphite. Theseresults will be shown in the later described tests.

Reaction products similar to that prepared in the above example can bemade using the previously-described hydroquinones and phosphoroustrihalides under the previously described reaction conditions. Forexample, a useful reaction product is obtained by reacting 3 moles of 2-methyl-6-tert-butyl-p-hydroquinone with one mole of phosphoroustrichloride at C. over a 4 hour period. Another useful reaction productis obtained by reacting two moles of 2,6-dicyclohexyl-p-hydroquinonewith one mole of phosphorous tribromide at C. in a xylene solvent overan 8 hours period. The reaction product is recovered by merely washingthe reaction mass with water and removing the solvent. Still anotheruseful reaction product can be prepared by reacting 4 moles of 2,6-di-(u-methylbenzyl)-p-hydroquinone with one mole of phosphoroustrichloride in a pressure vessel employing a xylene solvent and atemperature of 200 C. for 30 minutes. As before, the product can berecovered by merely Water Washing the reaction mass and removing theexcess solvent by distillation.

The compounds and reaction products of this invention are extremelyuseful as antioxidants in a wide variety of organic material normallysusceptible to deterioration in the presence of oxygen. Thus, liquidhydrocarbon fuels such as gasoline, kerosene and fuel oil are found topossess increased storage stability when blended with a stabilizingquantity of an additive of this invention. Like- Wise, hydrocarbon fuelscontaining organometallic additives such as tetraethyllead,tetramethyllead, methyl cyclopentadienyl manganese tricarbonyl,cyclopentadienyl nickel nitrosyl, ferrocene and iron carbonyl haveappreciably increased stability when treated with the additives of thisinvention. Furthermore, lubricating oils and functional fluids, boththose derived from naturally occurring hydrocarbons and thosesynthetically prepared, have greatly enhanced stability by the practiceof this invention. The additives of this invention are extremely usefulin stabilizing antiknock fluids against oxidative degradation. Forexample, the stabilizing additives of this invention find utility instabilizing a tetraethyllead antiknockfluid which containsethylenedichloride and ethylenedibromide.

The additives of this invention are effective in stabilizing rubberagainst degradation caused by oxygen or ozone. As used in thedescription and claims, the term rubber is employed in a generic senseto define a high molecular weight plastic material which possesses highextensibility under load coupled with the property of forciblyretracting to approximately its original size and shape after the loadis removed. Some examples are acrylic rubber, butadiene-styrene rubber'(SBR), chloroprene, chlorosulfonated polyethylene, fluorocarbonrubbers, isobutylene-isoprene (IIR), isoprene, butadiene,nitrile-butadiene rubber, polyisobutylene rubber, polysulfide rubbers,silicone rubbers, urethanes, India rubber, reclaimed rubber, balatarubber, gutta percha rubber, and the like. Both natural rubber andsynthetic rubbers such as neoprene, SBR rubber, EPT rubber, GR-N rubber,chloroprene rubber, polyisoprene rubber, EPR rubber, and the like, aregreatly stabilized through the practice of this invention.

The compounds of this invention are also useful in protecting petroleumwax against degradation. The additives also find use in thestabilization of fats and oils of animal and vegetable origin which tendto become rancid during long periods of storage because of oxidativedeterioration. Typical representatives of these edible fats and oils arelinseed oil, cod liver oil, castor oil, soy bean oil, rapeseed oil,coconut oil, olive oil, palm oil, corn oil, sesame oil, peanut oil,babassu oil, butter, lard, beef talloW, and the like.

The compounds of this invention are superior antioxidants for highmolecular weight polyolefins such as polyethylene (both high pressureand so-called Ziegler type polyethylene) polybutene, polybutadiene (bothcis and trans).

One of the features of the present stabilizers is that they do not causediscoloration when used in transparent, white, or light-colored organicmaterials such as white rubber or plastics such as polyethylene,polypropylene, and the like.

The amount of stabilizer used in the organic compositions of thisinvention is not critical as long as a stabilizing quantity is present,and can vary from as little as 0.001 weight percent to about 5 weightpercent. Generally, excellent results are obtained when from 0.1 toabout 3 weight percent of the stabilizer is included in the organiccompositions.

The following examples serve to illustrate the use of the stabilizers ofthe present invention in stabilizing some representative organicmaterials normally subject to deterioration in the presence of oxygen orozone.

EXAMPLE 5 A rubber stock is prepared containing the followingcomponents:

Component: Parts Pale crepe rubber Zinc oxide filler 50 Titanium dioxide25 Stearic acid 2 Ultramarine blue 0.12

Sulfur 3.00 Mercaptobenzothiazole 1.00

To the above base formula is added one part by weight oftris(3,5-di-tert-butyl-4-hydroxyphenyl)phosphite and, following this,individual samples are cured for 20, 30, 45 and 60 minutes,respectively, at 274 C. After cure, all of these samples remain white incolor and possess excellent tensile strength. Furthermore, they areresistant to degradation caused by oxygen or ozone on aging.

EXAMPLE 6 EXAMPLE 7 A butadiene acrylonitrile copolymer is prepared from68 percent 1,3-butadiene and 32 percent acrylonitrile. Two percent,based on the weight of the copolymer, of tris(3,5-diisopropyl-4-hydroxyphenyl)phosphite is added as an aqueous emulsionto the latex obtained from emulsion copolymerization of the butadieneand acrylonitrile monomers. The latex is coagulated with aluminumsulfate and the coagulum, after washing, is dried for 20 hours at 70 C.The synthetic copolymer so obtained is resistant to oxidativedegradation.

EXAMPLE 8 Three percent oftris(3,5-di-tert-octyl-4-hydroxyphenyl)phosphite as an emulsion insodium oleate is added to a rubber-like copolymer of 1,3-butadiene andstyrene containing 25 percent styrene. The resulting synthetic elastomerpossesses enhanced stability.

EXAMPLE 9 To a master batch of GR-N synthetic rubber containing 100parts of GR-N rubber, 5 parts of zinc stearate, 50 parts of carbonblack, 5 parts of road tar, 2 parts of sulfur and 2 parts ofmercaptobenzothiazole is added 5 percent, based on weight, oftris(3,5-di-sec-butyl-4- hydroxyphenyl)phosphite. After curing, asynthetic rubber is obtained of improved oxidative stability.

EXAMPLE 10 To a master batch of polyethylene having an average molecularweight of 1,000,000, a tensile strength of 6,700 p.s.i., a Shore Dhardness of 74 and a softening temperature under low load of C., isadded 5 percent of tris(3,5-di-tert-butyl-4-hydroxyphenyl)phosphite. Theresulting polyethylene possessess stability against oxidativedegradation and shows no tendency to yellow after extensive aging.

EXAMPLE 11 A linear polyethylene having a high degree of crystallinity(93 percent), and less than one branched chain per 100 carbon atoms, adensity of about 0.06 gram per ml. and which has about 1.5 double bondsper 100 carbon atoms, is mixed with 0.005 weight percent of tris(3,5-dicyclohexyl 4 hydroxyphenyl)phosphite. The resulting polyethylene isfound to possess stability against oxidative degradation.

EXAMPLE 12 To 100 parts of an ethylenepropylene terpolymer is added 3parts of tris(3tert-amyl-5-tert-octyl-4-hydroxyphenyl)phospite,resulting in an ethylenepropylene terpolymer of enhanced stability.

EXAMPLE 13 To 100 parts of an ethylenepropylene rubber is added 2 partsof tris(3-tert-nonyl-5-sec-octyl-4-hydroxyphenyl) phosphite, resultingin an EPR rubber stock of improved stability.

EXAMPLE 14 After the polymerization of polypropylene in a hexane solventemploying a Ziegler catalyst, the catalyst is neutralized with water andtris(3,5-di-tert-butyl-4-hydroxyphenyl)phosphite is added to the mixturein quantities such that, after evaporation of the solvent, a Zieglerpolypropylene is obtained containing 2 percent oftris(3,5-ditert-butyl-4-hydroxyphenyl)phosphite. This polypropylene isfound to possess excellent stability against degradation caused byoxygen or ozone. Furthermore, this polypropylene is found to resistdegradation at elevated tempera tures, even in the presence of oxygen.During this high temperature aging the Ziegler polypropylene shows notendency to discolor.

EXAMPLE 15 To 1,000 parts of a crystalline polypropylene prepared usinga Ziegler type catalyst is added 1 weight percent of the reactionproduct mixture of Example 4. The resulting mixture is melted andstirred, resulting in a molten polypropylene composition possessingexcellent resistance to thermal degradation.

EXAMPLE 16 To 1,000 parts of poly-cis-butadiene dissolved in benzene isadded 0.15 weight percent of the reaction product resulting from thereaction of 3 moles of 2-methyl-6-(amethylbenzyl)p hydroquinone with onemole of phosphorous tribromide at a temperature of 150 C. in a xylenesolvent for one hour. The reaction product is added as a 30 percentsolution in the xylene reaction solvent after merely washing thereaction mixture with water to remove acidic materials. The resultantpoly-cis-butadiene solution is transferred slowly into boiling waterwhich causes the water, benzene and the xylene to co-distill, leaving astabilized poly-cis-butadiene.

EXAMPLE 17 To 1,000 parts of a crystalline polypropylene made using aZiegler catalyst is added 1 weight percent of his (3,5 di tert butyl 4hydroxyphenyl)hydrogen phosphonate. The mixture is melted andimmediately stirred, giving a highly stable polypropylene.

EXAMPLE 18 To 1,000 parts of solvent-refined mid-continent neutrallubricating oil containing 0.05 percent zinc-dilaurylthiophosphate, 4percent of a poly laurylmethacrylate VI Improver and 0.05 percent of anover-based calcium sulfonate is added 0.05 percent ofbis(3,5-dicyclohexyl-4- hydroxyphenyDhydrogen phosphonate. The resultingoil is resistant to thermal and oxidant deterioration.

1 2 EXAMPLE 19 To 1,000 parts of an acrylonitrile-styrene-butadieneresin (ABS resin) is added 10 parts of carbon black and 5 parts oftris(3,5-di-tert-butyl-4-hydroxyphenyl)phosphite. The mixture is blendedin a Banbury mixer, resulting in a highly stable ABS resin.

EXAMPLE 20 To 1,000 parts of a gasoline containing 26.6 percentaromatics, 20.8 percent olefins, 52.6 percent saturates and having anAPI gravity of 62.1 is added 10 parts of tris( 3 tert butyl 5 cyclohexyl4 hydroxyphenyl) phosphite. The resulting gasoline is stable.

EXAMPLE 21 To 1,000 parts of gasoline containing 8.6 percent aromatics,7.9 percent olefins, 83.5 percent saturates and having an API gravity of68.5 is added 200 parts of the reaction product of Example 4. Theresulting gasoline is stable against oxidative degradation.

EXAMPLE 22 To 10,000 parts of a gasoline containing 20.0 percentaromatics, 41.2 percent olefins, 38.8 percent saturates and containingadditionally 1.5 grams of manganese per gallon as methylcyclopentadienyl manganese tricarbonyl is added 300 parts oftris(3-phenyl-5-tert-butyl-4-hydroxyphenyl)phosphite. The resultinggasoline containing a manganese antiknock was resistant to oxidativedegradation.

EXAMPLE 23 EXAMPLE 24 To 10,000 parts of gasoline containing 38.1percent aromatics, 7.3 percent olefins and 54.6 percent saturates andwhich contains 3.17 grams per gallon of lead as tetramethyllead, onetheory of chlorine as ethylenedichloride, 0.5 theory of bromine asethylenedibromide and 0.2 theory of phosphorus astris(fl-chloroisopropyl)thionophosphate is added 50 parts oftris[3-tert-butyl-5-(ot,udimethylbenzyl)-4-hydroxyphenyl]phosphite. Theresulting gasoline is resistant to degradation and also gives prolongedspark plug life on use.

EXAMPLE 25 An antiknock fluid composition is prepared by mixing together61.5 parts of tetraethyllead, 17.9 parts of ethylenedibromide, 18.8parts of ethylenedichloride and 1.3 parts oftris(3,5-di-tert-butyl-4-hydroxyphenyl)phosphite, resulting in a stableantiknock fluid composition.

EXAMPLE 26 To 1,000 parts of a commercial diesel fuel having a cetanenumber of 42 is added 5 parts of amyl nitrate and 4 parts oftris[3-n-propyl-5-(a-methylbenzyl)-4-hydroxyphenylJphosphite, resultingin a diesel fuel of high resistance to oxidative deterioration whichdoes not form gum or sludge on storage.

EXAMPLE 27 To 1,000 parts of a solvent-refined neutral oil viscosityindex and 200 SUS at F.) containing 6 percent of a commercialmethacrylate type VI improver is added 13 5 percent oftris[3,5-di-(a-methylbenzyl)-4-hydroxyphenyl[phosphite, resulting in astable lubricating oil.

EXAMPLE 28 To a solvent-refined crankcase lubricating oil having aviscosity index of 95 and a SAE viscosity of 10 is added 0.1 percent oftris(3,5-di-tert-dodecyl-4-hydroxyphenyl) phosphite. The resulting oilwas stable against oxidative degradation.

EXAMPLE 29 To 100,000 parts of a petroleum hydrocarbon oil having agravity of 303 API at 60 F., viscosity of 178.8 SUS at 100 F., aviscosity index of 154.2, and containing 1,000 parts of the reactionproduct of an alkenyl succinic anhydride where the alkenyl group has amolecular weight of 2,000, with a polyethylene amine, is added 200 partsof tris(3 tert amyl 5 tert octadecyl 4 hydroxyphenyl)phosphite. Theresulting lubricating oil possesses excellent dispersancy and isresistant to oxidative degradation.

EXAMPLE 3 To 100,000 parts of a commercially available pentaerythritolester having a viscosity at 100 F. of 22.4 centistokes and known underthe tradename of Hercoflex 600 is added 400 parts oftris(3,5-dicyclohexyl-4-hydroxyphenyl)phosphite. The resulting syntheticlubricating oil possesses improved resistance against oxidativedeterioration.

EXAMPLE 31 To 100,000 parts of dioctyl sebacate having a viscosity at210 F. of 36.7 SUS, a viscosity index of 159, and a molecular weight of427 is added 250 parts of bis(3-phenyl-S-tert-butyl-4-hydroxyphenyl)hydrogen phosphonate, resulting in asynthetic diester lubricating oil having improved resistance tooxidative degradation.

EXAMPLE 3 2 To 1,000 parts of a commercial coconut oil is added 5 partsof tris[3-tert-butyl-5-(a-trnethylbenzyl)-4-hydroxyphenyl]phosphite,resulting in a vegetable oil with good aging characteristics.

EXAMPLE 33 To 100,000 parts of lard is added 100 parts of tris(3 tertbutyl 5 cyclohexyl 4 hydroxyphenyl)phosphite, resulting in a lard havingresistance to rancidity.

The stabilizing additives of this invention are eminently useful asstabilizers in polyolefins such as polyethylene, polypropylene, and thelike. In this use they function as antioxidants, antiozonants and alsoas thermal stabilizers. They are extremely long lasting and highlyresistant to the formation of color.

In order to demonstrate their vastly superior stabilization effect testswere conducted using a commercial polypropylene. These tests are knownas Oven Aging Tests and are recognized in the plastic industry as anaccurate guide to oxidiative stability. In these tests small specimensof polypropylene are prepared containing the test stabilizer. These testspecimens are placed in an air circulating oven maintained at 150 C.Five replicates are made of each polypropylene-stabilizer compositionand the test criteria is the time in hours until three of the fivereplicates show signs of deterioration. Deterioration is evidenced bycracking, discoloration or any visual appearance of change in thespecimen.

Test specimens are prepared by mixing the test stabilizers withpolypropylene powder for 3 minutes in a Waring Blendor. The mixture isthen molded into a 6" x 6" sheet with a thickness of either 0.025" or0.0625". This is accomplished in a molding press at 400 F. under 5,000psi. pressure. Each sheet is then cut into /2 x 1" test specimens inorder to obtain the five replicate samples. These samples are thensubjected to the Oven Aging Tests.

In order to compare the stabilizing additives of this invention testswere carried out employing several commercially accepted stabilizersalong With the preferred stabilizer of the present invention. Theresults obtained are shown in the following table.

As the above table shows, the additive of the present inventionincreased the oven life of the polypropylene almost 700 times thatobtained without any additive, and from 11 to 14 times as much as thelife obtained with two commercially accepted antioxidants. Furthermore,the reaction product of Example 4 is even more eifective on a Weightbasis than its principal component.

Further tests were conducted demonstrating the effectiveness of theantioxidants in lubricating oil. One of these tests Was the Polyven'formTest. In this test, ml. samples were prepared from a mid-continentsolvent-refined neutral lubricating oil containing 0.1 weight percentferric oxide in the form of ferric hexoate and 0.05 weight percent leadbromide. One sample was subjected to the test unstabilized and the otherwas stabilized with 1 percent oftris(3,S-di-tertbutyl-4-hydroxyphenyl)phosphite. The test was run at twotemperatures. In one, the samples were heated to 300 F. and in the othertest they were heated to 325 F. In both tests, air was bubbled throughthe samples at a rate of 48 liters per hour. After 20 hours the test wasdiscontinued and the acid number and viscosity increase of the oilsamples determined. An increase in acid number or viscosity indicatesoxidative or thermal deterioration.

Percent viscosity Acid No. increase increase The above results show thestabilizers to be extremely eifective. The stabilized oil showed noincrease in acid number and only a fraction of the increase in viscosityshown by the unstabilized sample.

Another test conducted is the Panel Coker Test. In this test an oilsample is prepared containing one percent of the antioxidant testcompound. The oil employed is a mid-continent solvent-refined neutrallubricating oil. The oil sample is placed in a sump located beneath analuminum plate within the test apparatus. The aluminum plate is heatedto 625 F. The test is conducted by spraying the test oil against theheated plate for a 5 second interval and then allowing 55 seconds forthe oil to drain back into the oil sump. This one-minute cycle iscontinuously repeated over a 10 hour period, at which time the test isdiscontinued. The plate is allowed to cool and then rinsed with hexanes.The weight of the deposits formed on the plate is determined. Effectivestabilizers function to reduce the amount of deposit formed in thistest. The following table gives the amount of deposit formed when thetest was carried out On an unstabilized oil compared to the amountformed with the same oil containing a stabilizer within the presentinvention.

15 Additive: Deposit weight (mg) None 302 Tris(3,5di-tert-butyl-4-hydroxyphenyl) phosphite 144; 139

1 Replioates.

As this test shows, the additive effectively stabilizes the oil even atthe extreme temperature of 625 F. Thus, it can be seen that both thecompounds and the reaction products of the present invention are vastlysuperior to stabilizers available in the prior art.

The effectiveness of the present stabilizers can be enhanced stillfurther by employing synergistic mixtures of the stabilizers of thisinvention. The preferred synergists are those having the formula:

wherein n is an integer from 1 to 5, and R is selected from the groupconsisting of alkyl radicals containing from 120 carbon atoms, arylradicals containing from 6-20 carbon atoms, aralkyl radicals containingfrom 7-20 carbon atoms, and cycloalkyl radicals containing from 6-20carbon atoms. In the preferred synergist n is an integer from 1 to 3 andR is selected from the group consisting of alkyl radicals containingfrom 1018 carbon atoms. The most preferred synergists aredilaurylthiodipropionate and distearylthiodipropionate.

The ratio of synergist to stabilizing compound should be adjusted togive the desired protection at the least cost. Mixtures containing from1 percent synergist and 99 percent stabilizer to those containing 99percent synergist and 1 percent stabilizer can be employed. Best resultsare usually obtained with stabilizing mixtures containing from 50 to 66percent synergist and from 34 to 50 percent stabilizing compound.

The synergists can be employed to obtain increased stability using thesame concentration of stabilizer or they can be employed to obtain thesame stability with less of the stabilizer. Synergists are especiallyuseful in this latter application. Thus, althoughdilaurylthiodipropionate (DLTDP) is only moderately effective by itselfin stabilizing polypropylene, when used with a compound of the presentinvention a synergistic interaction occurs, resulting in a degree ofstability totally unexpected from the amount of stabilizers employed.This effect is shown in the following data obtained using thepreviously-dc scribed Oven Aging Test.

Cone. Sample Despite the fact that Sample 4, containing the synergisticmixture, contained only one-third as muchtris(3,5-di-tertbutyl-4-hydroxyphenyl)phosphite as did Sample 3, it canbe seen that it exhibited almost the same oven life. Likewise, Sample 6containing only one-third as much as the reaction product of Example 4as in Sample gives almost the same oven life. This can only beattributed to a synergistic interaction between DLTDP and thestabilizer, because DLTDP alone, even at 0.3 Weight percent (Sample 2),gave an oven life of only 288 hours.

Following are some examples of the synergistic stabilizing compositionsof the present invention.

3 3 tris 3 ,5 -di-tert-butyl-4-hydroxyphenyl phosphite 67%dilaurylthiodipropionate 1 6 50 tris (3-methyl-5-tert-butyl-4-hydroxyphenyl phosphite 5 0 dihexylthiodiacetate1% tris 3-ethyl-5-isopropyl-4-hydroxyphenyl phosphite 99diheptylthiodivalerate 99 tris3-rnethyl-5-cyclohexyl-4-hydroxypheny1)phosphite 1%di-n-octyl-thiodipropionatetris(3-methyl-5-(a-rnethylbenzyl)-4-hydroxyphenyl) phosphite 25%didecylthiodiacetate 25 tris 3-methyl-5-(a,a-dimethylbenzyl)-4-hydroxyphenyl phosphite 75%diundecylthiodibutyrate 25 tris( 3,5 -dicyclohexyl-4-hydroxypheny1hosphite 75 dioctadecylthiodipropionate tris 3-tert-butyl-5-ot-methylbenzyl) -4-hydroxyphenyl phosphite 20%dinonadecylthiodibutyrate 60% tris3-tert-dodecyl-5-sec-octadecyl-4-hydroxypheny1)phosphite 40%dieicosylthiodipropionate 10%tris(3,S-di-tert-butyl-4-hydroxyphenyl)phosphitedilaurylthiodipropionate 90%tris(3,5-di-tert-butyl-4-hydroxyphenyl)phosphite 10%dilaurylthiodipropionate 3 0 tris 3 ,5 -di-tert-butyl-4-hydroxyphenyl)phosphite 70% distearylthiodipropionate 10% of the reaction product of 3moles of 2,6-diisopropyl-p-hydroquinone with one mole of phosphoroustrichloride at C.

90% dilaurylthiodipropionate 90% of the reaction product of 2 moles of2,6-di-secbutyl-p-hydroquinone and one mole of phosphorous tribromide atC.

10% distearylthiodipropionate 30% of the reaction product of 4 moles of2,6-Cll(zxmethylbenzyl)-p-hydroquinone with one mole of phosphoroustrichloride at C.

70% dieicosylthiodibutyrate 70% of the reaction product of 3 moles of2-methyl-6- tert-amyl-p-hydroquinone with one mole of phosphoroustribromide at 75 C.

30% dioctadecylthiodiacetate 50% of the reaction product of 3.5 moles of2,6-dicyclohexyl-p-hydroquinone with one mole of phosphorous trichlorideat 125 C.

50% dicetylthiodiacetate The above synergistic stabilizer compositionsare beneficially employed in any of the previously-described organicmaterials normally susceptible to deterioration due to the effect ofoxygen. In Examples 5 through 33, each of the above synergisticcompositions can be substituted for the stabilizing additive of thepresent invention now shown, resulting in an organic composition ofincreased resistance to degradation from the effects of oxygen.

I claim:

1. A compound having the formula:

wherein R is selected from the group consisting of alphabranched alkylradicals containing from 3-8 carbon atoms, alpha-branched ara'ikylradicals containing from 818 carbon atoms and the cyclohexyl radical;and R is selected from the group consisting of alkyl radicals containingfrom 1-18 carbon atoms, aralkyl radicals containing from 7-18 carbonatoms, aryl radicals containing from 6-18 carbon atoms and thecyclohexyl radical.

2. The compound of claim 1 wherein R and R are tert-butyl radicals.

3. The compound of claim 1 wherein R and R are wmethylbenzyl radicals.

4. The compound of claim 1 wherein R and R are cyclohexyl radicals.

References Cited UNITED STATES PATENTS 9/1941 Bartram 260953 XR 1/1968Gleim et al 260953 XR U.S. C1. X.R.

P0-1050 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N'3n95638 Dated February 3, 1970 Inventor) Bernard R. Meltsner It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

rgolumn 2, line 3, 2-18" should read 8-18 line 28, 1 G-hydroquinoneshould read p-hydroquinone Column lines 35-37, that portion of theformula reading Pf [03X should read --P [91X 1 E IX Column 5, line 39,"(3,5-dihydroxycarby1" should read (5,5- dihydrocarbyl Column 6, lines50-32, that part of the equation reading -P should read -P Column 17,line 1, "3-8" should read 5-18 SIGNED AN'D SEALED JUL 1 4 I970 (SAttest:

Edward Fmdmmmrm 1:." sum, m. Attesting Officer C-olnnissioner of Patents

